Accessory roles of the vinculum breve of the flexor digitorum profundus and check-rein ligaments at the distal interphalangeal joint.

The vinculum breve of the flexor digitorum profundus tendon was found to apply traction to the volar plate on flexion of the distal interphanageal joint. It was also observed that the check-rein ligaments of the joint only became taut in the hyperextended position. This may account for the greater amount of passive hyperextension that can be achieved at the distal than the proximal interphanageal joint.